This invention relates to a centrifugal governor for controlling the r.p.m. of an internal combustion engine, and more particularly to an all-speed centrifugal governor of a novel construction which has percentages of speed changes freely settable in two or more different engine r.p.m. ranges.
Conventional centrifugal governors used in diesel engines include a type, such as all-speed type, in which a control spring is provided separately from the centrifugal weights for counteracting the centrifugal force thereof. The control spring has its spring constant adjustable by changing the angle of the line of action with respect to the spring by means of a control lever. The spring constant of the control spring determines the engine r.p.m. at which the governor starts governing action, and the percentage of speed change (hereinafter called merely "speed change").
However, only a single control spring is employed in such conventional type governor. Accordingly, the governing action starting r.p.m. and the speed change are kept in a fixed relationship to each other. That is, the speed change has a particular fixed value with respect to each governing action starting r.p.m. Furthermore, since the centrifugal force of the centrifugal weights becomes larger at an increased rate as the engine r.p.m. increases, the speed change of the governor decreases as the governing action starting r.p.m. increases.
For these reasons, the above-mentioned conventional type governor was found useless, for instance, in a specific case where it is necessary to obtain two different voltage currents which may be required of a driving device for welding generators according to the kind of welding required. In such case, the driving device must be operated under the control of an engine governor providing the same speed change in a higher r.p.m. range and in a lower r.p.m. range.